Brain Lesions (Cognitive Neuropsychology)

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Cognitive Psychology
Psychophysics
Neuropsychology
Cognitive Neuroscience
Electrophysiology (animal studies)
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Brain Lesions (Chapter 5)(Cognitive
Neuropsychology)

• The traditional approach to establishing a
  connection between the mind brain.
• Limitation of imaging (or any correlational)
  methods
• Does the activation have anything to do w/
  function?
• Car analogy
• One way to prove something is necessary
• Take it out

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History
LANGUAGE
VISION
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Levels of Analysis
Anatomical
Functional

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Advancements

• (1) MRI localize brain injury in vivo
• Very precisely locate injury and adapt tests
  accordingly
• patient populations identify groups of
  individuals with common brain injuries

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Advancement

• The use of control subjects

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Advancements

• (2) Cognitive psychology paradigms
• Area A is important for reading
• What are the components of reading?
• Perceiving letters
• Letter strings activate corresponding meanings
• Link words coherently
• What specific component is affected by area A
  damage?

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Disengage Shift Engage
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Disengage Shift Engage
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Cognitive Psychology Perspective

• Mental processes are composed of elementary
  mental operations
• These operations are localizable in time
• The operations are localizable in discrete,
  contiguous regions of the brain

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Single and Double Dissociations

• Start with a model/hypothesis
• Facial recognition and emotion recognition (based
  on facial features) are different processes

Emotion task
Recognition task
Performance ( Correct)
Region 1 (FFA)
Region Damaged
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Single and Double Dissociations

• Start with a model/hypothesis
• Facial recognition and emotion recognition (based
  on facial features) are different processes

Emotion task
Recognition task
Performance ( Correct)
Performance ( Correct)
Region 1 (FFA)
Controls
Region Damaged
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Problems with Single Dissociation

• Possible alternative interpretations
• Recognition task might be more difficult
• See task-resource artefact in text (p 82)

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Single and Double Dissociations

• Start with a model/hypothesis
• Facial recognition and emotion recognition (based
  on facial features) are different processes

Emotion task
Recognition task
Performance ( Correct)
Performance ( Correct)
Region 1 (FFA)
Controls
Region 2 (STS)
Region Damaged
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Double Dissociations (and fMRI)

• Start with a model/hypothesis
• Facial recognition and emotion recognition (based
  on facial features) are different processes

Emotion task
Recognition task
fMRI Activation
Region 1 (FFA)
Region 2 (STS)
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Problems w/ lesions

• A process must be localizable to specific regions
• Compounded by lack of specificity of lesions
• Lesion may disrupt connectivity other
  non-damaged areas might be non-functioning.
• Assumption that intact regions continue to
  function in the same way
• No timing information

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Transient Lesions

• Transcranial Magnetic Stimulation
• Magnetic field induced disruption of neural
  activity
• A brief pulse is applied that causes neural
  activity for 10s ms
• If the area is involved in the task, the dual
  firing (task and to the TMS pulse) results in
  behavioral disruption

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Advantageous

• Quickly reversible (no reorganization as w/ true
  lesions)
• Within-subject designs
• Moveable lesions
• Very focused ( 1 cm resolution)
• Precise timing

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